1. Field of the Invention
The present invention relates to a cooler for use in an exhaust gas recirculation (EGR) system in an internal combustion engine and particularly to a bypass around said cooler.
2. Description of the Related Art
Emissions regulations are requiring reduced emissions from vehicles, particularly the Euro 5, Bin 5 and US 06 regulations. To reduce the generation of nitrous oxides, it is known to recirculate exhaust gas through the engine. Under normal conditions the exhaust gas must be cooled before recirculation and it is known to pass the exhaust gas through an exhaust gas cooler. However, under “cold start” or low operating conditions, the gas can be over-cooled resulting in increased hydrocarbon emission and CO2 production.